Pediatric Cardiology at LLUCH: After Surgery

The Normal Heart and How It Works

Heart Diagram

The normal heart is a muscular pump consisting of four chambers. The two upper chambers, the right and left atria, receive blood returning from the body and lungs. The two lower chambers, the right and left ventricles, are the pumping chambers of the heart. The right ventricle is a low-pressure pump that pushes blood through the lungs, while the left ventricle is a high-pressure pump that pushes blood through the body. The dividing wall between the right and left sides of the heart is called the septum.

Blood Flow

The systemic (body) veins, also known as the vena cavae carry unoxygenated "blue" blood from the body into the right atrium. This blood has a dark or bluish color because the body tissues have used up all its oxygen. The blue blood goes from the right atrium to the right ventricle and is pumped through the pulmonary arteries to the lungs. In the lungs the blood picks up oxygen and released carbon dioxide and takes on a red color. This red oxygenated blood returns to the left atrium through the pulmonary veins. From the left atrium the blood travels to the left ventricle and is pumped through the aorta to the body, providing oxygen for the body tissues.

Heart Valves

The normal heart has four valves, which help direct the flow of blood. The four heart valves are: 1) Tricuspid valve (between the right upper chamber and the right lower chamber 2) Pulmonary valve (between the right lower chamber and the artery that leads blood to the lungs 3) Mitral valve (between the left upper chamber and the left lower chamber) 4) Aortic valve (between the left lower chamber and the artery that leads blood to the body). The valves open and close in perfect time to allow blood to flow forward and prevent blood from flowing backwards.

The Electrical System of the Heart

The heart has its own electrical system that regulates how fast the heart beats. The electrical impulses begin in an area of the heart called the sinoatrial node (SA node), or pacemaker of the heart. This impulse travels through a pathway in the heart causing the chambers to beat evenly.

Congenital Heart Defects

Congenital heart defects are structural problems of the heart present at birth. According to the American Heart Association approximately one in 100 children are born with a congenital heart defect. Defects range in severity from simple problems, such as "holes" between the chambers of the heart to severe malformations, such as the absence of one or more chambers or valves. No two heart defects are exactly alike. A cardiac surgeon will outline in detail the type of problem your child has and a corrective or palliative operation to be performed.